PTL 1 discloses an image synthesizing device configured to generate a synthetic image having an expanded dynamic range from a plurality of images. The image synthesizing device detects regions of a moving body included in these images by comparing a reference image with other images and determining the image in the region of the moving body included in the reference image as a moving body image. The image synthesizing device replaces the moving image region with a corresponding region of another image to generate a replacement image, and combines the replacement image and the reference image to generate a synthetic image. In this configuration, a synthetic image in which the moving body is considered is generated.
PTL 2 discloses an image processing device configured to generate a synthetic image from a plurality of images of a moving subject. The image processing device synthesizes a plurality of images according to a synthesis ratio calculated based on an evaluated value for brightness, an evaluated value for movement, and an evaluated value for contrast. In this configuration, even from images of a moving subject, a synthetic image having a natural appearance is generated.
PTL 3 discloses an image synthesizing device configured to synthesizing a plurality of images including an image of a moving subject and having different brightness. The image synthesizing device calculates movement data, which is an amount of shift between a reference image and a comparative image generated from the reference image and a non-reference image. For each of the reference image and the comparative image, the image synthesizing device calculates a pixel average for each of image blocks having a predetermined size, and determines whether the image block of the reference image is synthesized with the image block of the non-reference image associated with each other based on the movement data, based on the result of comparison between the difference between the pixel averages and a predetermined threshold. The ratio of the predetermined threshold and the ratio of synthesis of the image blocks are determined based on the pixel average of the image blocks of the reference image. In this configuration, blurring of the image is corrected, and a synthetic image with expanded dynamic range is obtained.